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How we age: the biology of aging

Why two people born the same year can age very differently, what scientists now call the hallmarks of aging, and what actually works.

Green Healthcare International · Patient education · Updated October 1, 2026

Chronological age and biological age

Chronological age is the number of years since you were born. Biological age describes how your body is actually functioning: your cells, organs and systems. Two 60-year-olds can be biologically very different. One may have the cardiovascular fitness and metabolic health of someone younger, and the other may have the risk profile of someone older.

The 12 hallmarks of aging

In 2013, and again in an updated 2023 review in the journal Cell, researchers led by Carlos López-Otín described the biological processes that drive aging. The 2023 update lists twelve:

1. Genomic instabilityDNA damage builds up faster than it is repaired.
2. Telomere attritionThe protective caps on chromosomes shorten.
3. Epigenetic alterationsThe chemical tags that switch genes on and off drift. This is what epigenetic clocks measure.
4. Loss of proteostasisCells become worse at keeping proteins correctly folded.
5. Disabled autophagyCellular “recycling” slows down.
6. Deregulated nutrient sensingInsulin and growth pathways stop responding normally.
7. Mitochondrial dysfunctionThe cell’s energy producers work less efficiently.
8. Cellular senescenceDamaged cells stop dividing but linger and release inflammatory signals.
9. Stem cell exhaustionThe body’s own repair cells decline in number and function.
10. Altered communicationSignals between cells and organs become disrupted.
11. Chronic inflammationLow-grade, persistent inflammation, sometimes called “inflammaging”.
12. DysbiosisThe balance of the gut microbiome shifts.

Where regenerative medicine fits

Several hallmarks explain why researchers study stem cells, Muse cells and exosomes. These include stem cell exhaustion, cellular senescence, altered cell-to-cell communication and chronic inflammation. That research is real and active.

No stem cell, exosome or other regenerative product is approved to treat aging itself. Aging is not an approved treatment indication for these products. Claims that a product “reverses aging” are not established medicine.

What is proven to help

The strongest evidence for healthy aging is still for well-known measures that address many hallmarks at once:

  • Regular physical activity, including strength training
  • Not smoking, and limiting alcohol
  • Good sleep
  • A balanced diet and a healthy weight
  • Treating blood pressure, blood sugar and cholesterol
  • Recommended screenings and vaccinations
  • Social connection and purpose

Sources and further reading

Source links checked October 1, 2026. Guidance and regulatory status can change. Refer to the responsible authority for the latest information.

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